Cable end seal, support and grounding assembly

ABSTRACT

Means for hermetically sealing, suspending and grounding a shielded multi-conductor cable relative to a pedestal-type terminal board facility. The components utilized for these purposes include a first solderless terminal assembly embracing and clamping the cable shield and sheath together, a pair of compressable solderless terminals telescoped over the opposite ends of a combination cable suspension and grounding conductor strap anchorable at one end to the clamping bolt of the first solderless terminal assembly and the other end to the terminal board facility. A slit sleeve loosely embraces the cable end and is charged with potting compound thereby hermetically sealing together the cable end, the sleeve and the adjacent components of the suspension unit and precluding the entry of moisture into the cable.

United States Patent [191 Thompson et al.

[ 1 May 8, 1973 [54] CABLE END SEAL, SUPPORT AND GROUNDING ASSEMBLY [22]Filed: Jan. 19, 1971 [21] Appl. No.: 107,794

[52] 11.8. CI. ..l74/78, 174/38, 174/60, 339/95 R, 339/176 R, 29/628[51] Int. Cl. ..H02g 15/02 [58] Field of Search ..339/14, 95, 176,339/177, 59-61; 174/38, 60, 75, 76, 78, 41, 51

[56] References Cited UNITED STATES PATENTS 3,499,972 3/1970 Smith..l74/88 2,083,606 6/1937 Johansson ..339/266 R 3,593,002 6/1969 Hebert..219/541 3,594,691 7/1971 Neal ..339/29 U Q 5 D IIlII 3,253,247 5/1966VOS ..l74/78 Primary ExaminerMarvin A. Champion AssistantExaminer-Robert A. Hafer Attorney-Sellers and Brace [57] ABSTRACT Meansfor hermetically sealing, suspending and grounding a shieldedmulti-conductor cable relative to a pedestal-type terminal boardfacility. The components utilized for these purposes include a firstsolderless terminal assembly embracing and clamping the cable shield andsheath together, a pair of compressable solderless terminals telescopedover the opposite ends of a combination cable suspension and groundingconductor strap anchorable at one end to the clamping bolt of the firstsolderless terminal assembly and the other end to the terminal boardfacility. A slit sleeve loosely embraces the cable end and is chargedwith potting compound thereby hermetically sealing together the cableend, the sleeve and the adjacent components of the suspension unit andprecluding the entry of moisture into the cable.

14 Claims, 5 Drawing Figures CABLE END SEAL, SUPPORT AND GROUNDINGASSEMBLY This invention relates to grounding and sealing facilities forshielded multi-conductor cables and more particularly to highlyversatile components adapted to be assembled between a terminal boardsupport or pedestal and the cable end, and providing a high strengthelectrical and mechanical connection between the pedestal and the cable.

Various expedients have been resorted to heretofore to terminateunderground cables at terminal board facilities with provision forconnecting the cable conductors to electrical equipment or to othercables. Not only must the cable end be sealed closed to safeguardagainst the entry of moisture, but means must be provided for anchoringthe cable end to a suitable support to avoid stressing the individualconductors. Additionally, it is important that the cable shield beprovided with an adequately strong and reliable ground connection.

The present invention provides simple, rugged, easily operatedcomponents meeting the foregoing and other needs in a highlysatisfactory manner. These components include a set of three solderlessterminal assemblies, a high strength combination grounding conductor andcable suspension strap, and an enclosure sleeve for the cable endfillable with sealing compound after all the parts have been properlyadjusted and checked for accurate assembly. One solderless terminalassembly utilizes the strength of the cable sheath to greatly augmentthe strength of the shield itself in providing a high strengthelectrical and mechanical connection to the cable shield. Additionally,one of a pair of simple, one-piece solderless connectors telescoped overthe opposite ends of an imperforate ductile suspension strap serves,when tightened, to provide a high strength mechanical and electricalconnection between the cable shield solderless terminal and the lowerend of the grounding strap and the other serves to anchor the upper endof the strap in like manner to the terminal board pedestal. The sleeveused to encapsulate the cable end is slit and formed of flexiblematerial so that it is readily assembled about the cable after all otherparts of the assembly have been completed following which the sleeve ischarged with potting compound selected to form a strong hermetic bondwith all surfaces in contact therewith.

Accordingly, it is a primary object of the invention to provide a newand improved mode of sealing a cable end and including provision forgrounding the cable shield and for rigidly anchoring the cable end to asuitable fixed support.

Another object of the invention is the provision of simple, ruggedcomponents including a plurality of solderless terminal assembliescooperating to provide a strong mechanical and electrical connectionbetween the cable shield and a grounded terminal board pedestal.

These and other more specific objects will appear upon reading thefollowing specification and claims and upon considering in connectiontherewith the attached drawing to which they relate.

Referring now to the drawing in which a preferred embodiment of theinvention is illustrated:

FIG. 1 is a perspective view showing one preferred embodiment of-theinvention fully assembled to a typical cable terminal board pedestal;

FIG. 2 is a fragmentary cross sectional view on an enlarged scale takenalong line 2--2 on FIG. 1;

FIG. 3 is a cross sectional view taken along line 3-3 on FIG. 2;

FIG. 4 is a longitudinal sectional view of the solderless terminal inassembled position taken through one row of the bonding projections; and

FIG. 5 is a perspective view of the bonding bar being inserted betweenthe legs of the terminal clip.

Referring initially more particularly to FIG. 1, there is shown aconventional multiple conductor cable 10 having one end projectingupwardly through an access box 11 having its lower end in communicationwith an underground cable duct system. Box 11 normally terminatessomewhat above the surrounding ground level and provides an anchorageand support for a metal framework 12 of a pedestal-type terminal boardfacility equipped in known manner with electrical accessories or withterminal board strip 15 to which the cable conductors are secured. Thisfacility is normally enclosed by an inverted hood, not shown, having itslower end suitably secured to the rim of access box 1 1. The details ofsuch pedestals and their many uses are well known to those skilled inthis art and need not be described in greater detail.

The means provided by this invention for supporting the cable end in anupright position adjacent the equipment or terminal board to which it isto be attached will be best understood by reference to FIGS. 2 and 3.Such cables customarily comprise a multiplicity of conductors 15surrounded by an inner tubular sheath of insulation 16 embraced by athin-walled metallic electrical shield 17 underlying the outer tough,thick, elastomeric cable sheath 18.

In preparing each cable end for connection to the terminal boards 13 asuitable length of the sheath, shield and inner liner is removed toexpose and free the ends of individual conductors l5. Shield 17 andsheath 18 are usually cut back by the same amount and so as to leave aninch or two length of layer 16 exposed.

The next step in the operation is to provide a strong electrical andmechanical connection to the thin, fragile electrical shield layer 17.This is preferably accomplished according to this invention by firstslitting cable sheath 18 for a distance of several inches from one end,as is indicated at 20 in FIG. 2.-This permits the slit portions ofshield 17 and sheath 18 to be expanded away from the conductors whilemaking a hole through each to receive the threaded shank of a solderlessconnector. This connector comprises an inner shoe 22, a flexible springshim 23, and outer metallic shoe 24 and a threaded shank or bolt 25secured to inner shoe 22 and extending loosely through aligned openingsin shim 23, shield 17, sheath 18 and outer shoe 24. Shim 23 has agreater curvature than shoe 22 and is formed with a multiplicity oflow-height sharp-edged burrs efi'ective facing outwardly to penetrate afilm of insulation often present on the inner surface of shield 17. Thissolderless terminal assembly is of the same general constructiondisclosed in and claimed in our copending application for US. LettersPatent, Ser. No. 765,158, filed Oct. 4, 1968.

This assembly is installed while the shield and sheath are expanded awayfrom the conductors, as is permitted by slit 20, thereby facilitatingthe insertion of threaded shank 25 from the inner ends of the alignedassembly holes. Prior to placing the outer shoe 24 over the shank it isdesirable to secure the sheath snugly about the conductors and to holdthe same snugly thereagainst by one or more servings of friction tape 27for a distance extending beyond the opposite ends of slit 20. Thishaving been accomplished an inner clamping nut 28 is assembled to shank25 after placing the outer shoe 24 in assembled position. Nut 28 is thenthoroughly tightened causing the sharp burrs on shim 23 to scratch andpenetrate through any insulating film present on shield 17 and so as toform a multiplicity of electrical contacts with the shield. The highpressure applied to layer 17,18 sandwiched between the inner and outershoes compresses the parts into high pressure contact with one another.Additionally the wide surfaces of the inner and outer shoes are forcedinto high pressure frictional contact with the respective layers therebydistributing any load forces applied to the solderless assembly to alarge area portion of both shield 17 and the tough cable sheath 18.

The assembler may now proceed to complete the assembly by attachingsimilar solderless connectors to the opposite ends of a heavy gaugestrip of ductile metal 30. This strap is cut to the proper length tosuspend the end of cable at the proper height relative to the terminalboard of pedestal 12 to which it is to be connect'ed. Desirably, strap30 is free of perforations and is of uniform width and thickness fromendto end in order that its full strength and capacity may be utilized forboth its mechanical and electrical functions. Although its opposite endsmay be provided with holes fitting over the threaded shank 25 of theabove described solderless cable terminal and to a bolt holding thestrap anchored to the frame of pedestal 12, it is preferred that thestrapbe free of weakening openings of any kind and instead that the typeof solderless terminals 35 shown in FIGS. 2 and 4 be utilized.

Solderless terminals 35 comprise a heavy gauge U- shaped clip formed ofhigh strength spring stock. The bight portion of each is provided with awide opening 36 having a close sliding fit with strap 30. In theirrelaxed condition, the clip legs 37,37 flare outwardly and their freeends are provided with a pair of aligned openings 38 to receive aclamping bolt 25. An important feature is the provision on the innersurfaces of legs 37 of a multiplicity'of sharpcrested projections formedby making sharp-bottomed depressions 41 from the outer or exterior sidesof each of the legs. Projections 40 are preferably arranged in rows withtheir sharp edges facing one another from the inner faces of the cliplegs.

Terminals 35 are anchored immovably to the ends of strap 30 by insertingthe ends through openings 36 of the clips and then assembling openings38 either over threaded shank 25 or a bolt 43 passing through a hole inone of the metallic structural members 44 of pedestal 12. Beforetightening either of the bolts care should be exercised to note that theend of the strap is close to or in contact with the bolt. Thereafter,nuts 45 of the bolts are tightened against the outer legs of thesolderless terminal. Owing to the tempered nature of the materialcomprising clip 35; the sharp crested projections 40 readily penetratethe ductile material of strap 30 as the legs are forced into highpressure contact with its opposite faces. ln this manner there isprovided a powerful interlocking mechanical and electrical grip betweenthe strap and each leg of the clip. The completed assembly utilizes thefull strength of the strap and the components associated therewith bothfor mechanical strength and electrical current carrying capacity.

The foregoing operations having been completed,

the operator encapsulates the end portionof the cable utilizing thetapering split sleeve 50. This sleeve has a cylindrical body and aconical lower end 51 and is split fron end to end in order that thesemi-flexible elastomeric material of which it is composed can beexpanded sufficiently in girth for assembly about the suspended cable toenclose the portion opposite the lower end of suspension strap 30.Normally, the installer cuts away a portion of the pointed end 51 of thesleeve as necessary to form a snug fit with the particular size cablebeing encapsulated. The split in the sleeve is preferably closed by asemi-flexible sealing strip 54 of H-shape in cross section as bestappears in FIG. 3. The free edges of this strip have resilient grippingaction with the sidewalls of the sleeve as the strip is telescopedastride the split from the upper end of the sleeve.

Before charging the sleeve with potting compound it is desirable toserve its lower end with several convolutions of friction tape 56 toavoid escape of potting compound. This having been done the top of thesleeve is charged with a fluent potting compound 57 of any well knowncomposition. Preferably a thermosetting resinous compound is desirablebecause of its pronounced sealing characteristics for a wide variety ofdifferent materials. As soon as the potting compound takes a set allparts of the assembly enclosed by sleeve 50 become hermetically sealedagainst the entry of moisture-and all parts are prevented fromloosening. No moisture can enter the cable since the compound readilypenetrates between the exposed surfaces of conductors l5 and fills allvoids between these conductors.

While the particular cable end seal, support and grounding assemblyherein shown and disclosed in detail is fully capable of attaining theobjects and providing the advantages hereinbefore'stated, it.is to beunderstood that it is merelyillustrative of the presently preferredembodiments of. the invention and that no limitations are intended tothe detail of construction or design herein shown other than as definedin the appended claims.

We claim:

1. That improvement in terminating and hermetically sealing the end of amulti-conductor cable at a terminal facility which comprises removing alength of the cable sheath to expose the ends of the cable conductors,slitting the sheath sufficiently to insert an inner clamping shoe and abolt extending outwardly through a hole therefor in the sheath whichhole has a continuous perimeter and through a hole in an outer clampingshoe anchoring a grounding conductor strap of rectangular cross-sectionto the outer end of said bolt by the aid of a nut assembled to the bolteffective as it is tightened to clamp the cable sheath tightly betweensaid inner and outer shoes and said grounding conductor strap,,andembedding and sealing the portion of the cable end in the vicinity ofsaid clamping bolt in potting compound with the individual conductorsand the free end of said grounding conductor strap projecting outwardlybeyond said sealing compound.

2. That improvement defined in claim 1 characterized in providing saidgrounding conductor strap with solderless terminal means at the outerfree end thereof and securing the same rigidly and in good electricalcontact to grounded conductive means.

3. That improvement defined in claim 2 characterized in utilizinggrounding conductor strap which is free of openings from end to endthereof.

4. That improvement defined in claim 3 characterized in utilizingsolderless terminal means comprising a U-shaped terminal clip having awide opening in the bight portion thereof sized to receive the end ofsaid conductor strap, said terminal clip having a plurality ofheat-hardened sharp-crested projections formed on the inner surfacethereof effective to bite into said conductor strap assembled throughsaid bight opening as the legs of said clip are compressed against thejuxtaposed surfaces of said conductor strap, the free ends of the cliplegs having aligned openings through which said clamping bolt extends,and applying nut means to the outer end of said bolt for compressingsaid clip legs together to anchor said conductor strap immovablyassembled between the legs of said clip.

5. That improvement defined in claim 4 characterized in that saidsharp-crested projections on said clip are arranged in rows extendinglengthwise of said clip legs.

6. That improvement defined in claim 4 charac terized in that saidsharp-crested projections project toward one another from the inner faceof each leg of said clip.

7. That improvement defined in claim 3 characterized in the provision ofsolderless terminal means assembled over the opposite ends of saidconductor strap and comprising a U-shaped heat-hardened clip havinginwardly projecting sharp-crested projections effective to bite intosaid conductor strap after an end thereof has been inserted through anopening in the bight portion of said U-shaped clip and as the clip legsare compressed against the opposed faces of the respective ends of saidconductor strap, one of said clips having aligned openings in its legends mountable over the end of a clamping bolt and the other of saidclips having aligned openings in its leg ends to receive a boltclampable to a grounded conductive support pedestal for the cable end.

8. That improvement defined in claim 1 characterized in the provision ofa tubular sleeve surrounding and enclosing said potting compound.

9. That improvement defined in claim 8 characterized in that said sleeveis formed of semi-rigid material and split lengthwise thereof to permitexpansion of its sidewalls sufficiently for assembly of the sleeve aboutthe cable from the side thereof, and semi- 'rigid strip means havingoppositely facing grooves therealong sized to have a snug fit over arespective adjacent edge of said split in said sleeve, said pottingcompound being bondable to the interior surfaces of said I embrace acable sheath, and gasket means at the smaller end of said sleevecooperating with the cable sheath to hold the potting compound captivewhile setting.

11. That improvement defined in claim 7 characterized in that said cableend projects upwardly and terminates at a level spaced below an anchorpoint on said support pedestal, and said conductor strap projectingupwardly from said cable end being securely clamped to said anchor pointand serving as a combined grounding conductor for the cable shield and ahigh strength suspension support between said pedestal and said cableend.

12. That improvement in electrically and mechanically anchoring amulti-conductor shielded cable encased in a tough sheath to a terminalboard pedestal which comprises: a first solderless terminal assemblyhaving inner and outer wide area metallic shoes held clampedrespectively against the inner surface of said shield and the outersurface of said sheath by a clamping bolt, a pair of U-shaped one-piecesolderless terminal clips formed from wide strip stock of uniformrectangular cross section and having an opening in their bight portionstelescoped over the opposite ends of a heavy gauge ductile groundingstrap of rectangular shape in cross section with the free ends of theclip legs projecting beyond a respective end of said strap, the innersurfaces of said clip legs having hardened sharpcrested projectionsbiting into the juxtaposed strap surfaces as the clip legs arecompressed toward one another and against the juxtaposed surfaces ofsaid strap thereby to anchor said clips immovably to the strap ends, thelower one of said clips being clamped to the outer end of the clampingbolt of said first solderless terminal assembly by the tightening of thelatter, and the upper one of said clips being rigidly clamped to saidterminal board pedestal, and sleeve means embracing the cable end andthe lower end of said strap and charged with potting compoundhermetically sealing together the components in contact therewith.

13. That improvement defined in claim 12 characterized in that saidstrap is imperforate and arranged vertically between said terminal boardpedestal and said first solderless terminal assembly.

14. That improvement defined in claim 12 characterized in that saidductile strap is cut to size at the time of assembly to a given cableend and so that said strap is loaded in tension upon the anchorage ofits upper end to said pedestal.

i 101 i i

1. That improvement in terminating and hermetically sealing the end of a multi-conductor cable at a terminal facility which comprises removing a length of the cable sheath to expose the ends of the cable conductors, slitting the sheath sufficiently to insert an inner clamping shoe and a bolt extending outwardly through a hole therefor in the sheath which hole has a continuous perimeter and through a hole in an outer clamping shoe anchoring a grounding conductor strap of rectangular cross-section to the outer end of said bolt by the aid of a nut assembled to the bolt effective as it is tightened to clamp the cable sheath tightly between said inner and outer shoes and said grounding conductor strap, and embedding and sealing the portion of the cable end in the vicinity of said clamping bolt in potting compound with the individual conductors and the free end of said grounding conductor strap projecting outwardly beyond said sealing compound.
 2. That improvement defined in claim 1 characterized in providing said grounding conductor strap with solderless terminal means at the outer free end thereof and securing the same rigidly and in good electrical contact to grounded conductive means.
 3. That improvement defined in claim 2 characterized in utilizing grounding conductor strap which is free of openings from end to end thereof.
 4. That improvement defined in claim 3 characterized in utilizing solderless terminal means comprising a U-shaped terminal clip having a wide opening in the bight portion thereof sized to receive the end of said conductor strap, said terminal clip having a plurality of heat-hardened sharp-crested projections formed on the inner surface thereof effective to bite into said conductor strap assembled through said bight opening as the legs of said clip are compressed against the juxtaposed surfaces of said conductor strap, the free ends of tHe clip legs having aligned openings through which said clamping bolt extends, and applying nut means to the outer end of said bolt for compressing said clip legs together to anchor said conductor strap immovably assembled between the legs of said clip.
 5. That improvement defined in claim 4 characterized in that said sharp-crested projections on said clip are arranged in rows extending lengthwise of said clip legs.
 6. That improvement defined in claim 4 characterized in that said sharp-crested projections project toward one another from the inner face of each leg of said clip.
 7. That improvement defined in claim 3 characterized in the provision of solderless terminal means assembled over the opposite ends of said conductor strap and comprising a U-shaped heat-hardened clip having inwardly projecting sharp-crested projections effective to bite into said conductor strap after an end thereof has been inserted through an opening in the bight portion of said U-shaped clip and as the clip legs are compressed against the opposed faces of the respective ends of said conductor strap, one of said clips having aligned openings in its leg ends mountable over the end of a clamping bolt and the other of said clips having aligned openings in its leg ends to receive a bolt clampable to a grounded conductive support pedestal for the cable end.
 8. That improvement defined in claim 1 characterized in the provision of a tubular sleeve surrounding and enclosing said potting compound.
 9. That improvement defined in claim 8 characterized in that said sleeve is formed of semi-rigid material and split lengthwise thereof to permit expansion of its sidewalls sufficiently for assembly of the sleeve about the cable from the side thereof, and semi-rigid strip means having oppositely facing grooves therealong sized to have a snug fit over a respective adjacent edge of said split in said sleeve, said potting compound being bondable to the interior surfaces of said sleeve and to said strip means as the same takes a set.
 10. That improvement defined in claim 9 characterized in that one end of said tubular sleeve is frusto-conical with the smaller end thereof sized to closely embrace a cable sheath, and gasket means at the smaller end of said sleeve cooperating with the cable sheath to hold the potting compound captive while setting.
 11. That improvement defined in claim 7 characterized in that said cable end projects upwardly and terminates at a level spaced below an anchor point on said support pedestal, and said conductor strap projecting upwardly from said cable end being securely clamped to said anchor point and serving as a combined grounding conductor for the cable shield and a high strength suspension support between said pedestal and said cable end.
 12. That improvement in electrically and mechanically anchoring a multi-conductor shielded cable encased in a tough sheath to a terminal board pedestal which comprises: a first solderless terminal assembly having inner and outer wide area metallic shoes held clamped respectively against the inner surface of said shield and the outer surface of said sheath by a clamping bolt, a pair of U-shaped one-piece solderless terminal clips formed from wide strip stock of uniform rectangular cross section and having an opening in their bight portions telescoped over the opposite ends of a heavy gauge ductile grounding strap of rectangular shape in cross section with the free ends of the clip legs projecting beyond a respective end of said strap, the inner surfaces of said clip legs having hardened sharp-crested projections biting into the juxtaposed strap surfaces as the clip legs are compressed toward one another and against the juxtaposed surfaces of said strap thereby to anchor said clips immovably to the strap ends, the lower one of said clips being clamped to the outer end of the clamping bolt of said first solderless terminal assembly by the tightening of the latter, and the upper one of said clips being rigidly clamped to said terminal board pedestal, and sleeve means embracing the cable end and the lower end of said strap and charged with potting compound hermetically sealing together the components in contact therewith.
 13. That improvement defined in claim 12 characterized in that said strap is imperforate and arranged vertically between said terminal board pedestal and said first solderless terminal assembly.
 14. That improvement defined in claim 12 characterized in that said ductile strap is cut to size at the time of assembly to a given cable end and so that said strap is loaded in tension upon the anchorage of its upper end to said pedestal. 